Inkjet print heads typically include a ‘jet stack,’ a stack of plates that form manifolds and chambers of an ink path from an ink reservoir to an array of single jets, each of which having a nozzle. Ink enters the jet stack from the reservoir and is routed through the ink path to the final plate that contains an array of nozzles through which the ink selectively exits the jet stack. In a selective fashion, signals drive an array of transducers that operate on pressure chambers or body chambers associated with each single jet. When a particular transducer receives a signal to jet the ink, it pushes ink out of the body chamber through the jet and its nozzle to the printing surface.
The desire for higher resolution images, and increased throughput, results in the need for higher and higher packing density for the jets. The packing density is the number of jets that exist within some predefined space. Space requirements for each jet limit the number of jets that can fit within that space. Current print head designs typically have a serial flow path. Fluid flows into the body chamber through a first discrete fluid element and then flows out of the body chamber through a second discrete fluid element that leads to the corresponding single jet aperture. Each of these fluid elements use a certain amount of real estate associated with the jet stack and require some distance between them for separation as well. These effects act to limit the number of single jets that can be packed within the space of any given jet stack.
As set out in U.S. patent application Ser. No. 14/095,127, filed Dec. 3, 2013, it is possible to use a parallel flow single jet architecture to increase packing density. However, this single jet architecture lacks crossflow of ink into and out of the driver body volume that exists in the serial jet architectures. Further, if the parallel flow single jet architecture is oriented with the exit portion of the jet facing downward during use, and a bubble is introduced into the jet, buoyancy will tend to direct the bubble into the body chamber. Once inside the body chamber, and due to the lack of crossflow of ink into and out of the driver body, the bubble is difficult to remove without changing orientation of the print head, applying vacuum, or through slow absorption into the jetting fluid. As long as the bubble remains within the body chamber, the jet is rendered non-functional.